Neuronal galvanotropism
Neuronal galvanotropism is the ability to direct the outgrowth of neuronal processes through the use of an extracellular electric field. This technique has been researched since the late 1920s and has been shown to direct the formation of both axonic and dendritic processes in cell culture. It is only possible to direct outgrowth of in vitro preparations at this point. In vitro preparations involve the use of a culture dish, in which there is a species-specific neuronal growth factor. Neurons are removed from a chosen animal, plated onto the dish and allowed to grow (often kept in incubation). The application of an extracellular electric field shows that the cells will grow processes in a direction that demonstrates the direction of the applied electric field. This could be either in the direction of the cathode or anode, depending on the type of substrate the cells are plated onto.